Shoe shank stiffener and method of securing it to a sole member



p l938- R. B. BARTELS 2,129,556

SHOE SHANK STIFFENER AND METHOD OF SECURING IT TO A SOLE MEMBER Filed April '26, 1935 Patented Sept. 6, 1938 UNITED STATES PATENT OFEQE Reinhard B. Bartels, Marblehead, Mass.

Application April 26,

4 Claims.

This invention relates to metal shoe shank stiffeners and to their securement in shoes, and while not restricted to metal stiffeners of any particular" type, the invention has been developed more particularly in connection with stiffeners made of tempered steel, such stiffeners having presented special difficulties in connection with their securement which have been overcome successfully by this invention.

Heretofore ithas been usual practice to provide tempered steel stiffeners with holes through which securing devices such as tacks have been passed. This not only requires the use of fastener devices separate from the stiffener itself with the additional expense of such separate devices, but it involves more operations in assembly of the parts and thus further increases the cost of manufacturing the shoe. Further it fails to insure the desired strength and rigidity of securement, often permitting some initial play between the parts which increases with use and some times results in breaking of the securing devices so that the stiffener may become displaced.

Attempts have been made to employ prongs integral with the stiffener for clinching into the adjacent shoe part as is common practicein connection with non-tempered stiffeners, but the heat treatment to which the stiffener is subjected in the hardening and tempering operation causes these prongs to be so brittle that they break off when it is attempted to bend them in the clinching operation. Attempts to soften the prongs without adversely affecting the adjacent portions of the stiffener have been unsuccessful. In accordance with the present invention the stiffener is provided with integral fastening elements but they are so formed that bending of them is not resorted to in securing the stiffener. Instead, the fastening elements are made slightly longer than the thickness of the adjacent sole member and after being driven therethrough they are slightly up-set and headed over at the opposite face of that member, the relationship of the elements to each other being such as to cooperate with the material to effect a secure bond with only a slight amount of heading over. This heading over can be effected in a tempered steel shank without difficulty, provided only that the carbon content of the steel be kept reason- 1935, Serial No. 18,285

ener together and to simultaneously drive the securing elements through the shoe part and head them over.

For a more complete understanding of this invention, reference may be had to the accompanying drawing in which Figure 1 is a perspective showing a metal stiffener and a fiber shank piece secured together and illustrating the invention. I

Figures. 2 and 3 are diagrammatic longitudinal sections showing in successive stages the manner in which the shank piece and metal stiffener are simultaneously molded and secured together;

Figures 4', 5 and 6 are diagrammatic fragmentary sections to a larger scale showing the manner in which the securing elements are driven through the sole part and headed over.

Figure 7 is a fragmentary perspective of a portion of the metal stiffener showing a modification.

Figure 8 is a detail section on line 8-8 of Figure 7.

Referring to the drawings, Figure 1 shows a shoe unit comprising a fibrous sole member such as a shank piece I to which is secured a metal shank stifiener 2. As shown this shank stiffener is: provided with pairs of spaced prongs 5 integral therewith for securement of the stiffener to the member I. As shown best in Figure 4, these prongs are struck from the material of the stiffener 2 in opposite directions so as to extend from one face thereof at angles a not greater than 90. These angles may be slightly less than 90 if desired, although it is preferred that these prongs should be substantially parallel to each other, it being not desired to cause any bending of these prongs during the securing operation as has been desired heretofore when metal shank stiffeners are intended to be secured by integral prongs clinched within the body of an adjacent sole member. These prongs 5 are preferably slightly tapered, being narrower at their ends than at their roots, this being clearly indicated by the shapes of the openings 6 extending through the stiffener and left by the displacement of the prong material.

As shown best in Figure 5, the prongs 5 are slightly longer than the thickness of the sole member I. This sole member may be made of leather, though commonly it is made of leatherboard or other suitable sheet fibrous material. With a leatherboard having a thickness of .075 inch, the prong length may be .085 inch, so that when the parts are secured together, these prongs are driven entirely through the body of the member l and are then headed over substantially into the body of the material as shown at 8 in Figure 6. Preferably the metal stiffener is first molded to the desired contour as shown in Figure 2, and then the stiffener with the member superposed thereon is placed between suitable forms such as I0 and H so that the sole member l is molded to the contour of the shank stiffener, more particularly to take its longitudinal curvature, and simultaneously therewith the prongs 5 are driven through the body of the member I and headed over as illustrated in Figure 6. The prongs 5 are made of such size and are spaced apart at such a distance in pairs that they enclose between them and compress a portion l2 of the member I, condensing it so that it is of sufficient hardness to firmly secure the prongs within the body of the member I with a relatively small amount of heading over of the prongs 5, the between portion l2 acting in the nature of an integral reinforcement or rivet-like portion of the member I gripped between the adjacent prongs 5 between their bases and heads. The prongs 5 are, however, spaced sufficiently far apart so as to avoid any substantial weakening of the bond between this portion l2 and the adjacent portions of the member I. If the prongs 5 are arranged too close and make too large holes through the member I they have a tendency to tear out the portion [2 from the body of the member I, thus weakening the bond between the metal stiffener and the member I. If they are too widely spaced in proportion to their cross sectional areas so that they do not compress the portion I2 between them to a sufficient extent, this portion I2 remains so soft that the holding power of the headed over portions thereon is small, so that under these conditions a less secure bond between the metal stiffener and the member I is produced.

With the fiberboard of medium softness and a stiffener of 19 gage U. S. standard, the spacing between the prongs may be, say, approximately 4 of an inch, the prongs being, say, 27 of an inch wide, at their bases and fiof an inch wide at their ends.

It is preferable that these prongs be arranged in pairs spaced apart lengthwise of the metal stiffener where this metal stiffener is cut lengthwise of the grain of the metal, which is lengthwise of the direction of rolling to which the metal was subjected in reducing it to sheet form. This results in the bend at the root of the prongs being crosswise of the grain of the metal which causes the prongs to be less brittle at their roots than where the grain runs at right angles to such direction.

Where the carbon content of the steel of which the stiffeners are made is kept fairly low, little, if any, exceeding 50%, satisfactory tempering of the stiffeners can be produced, while at the same time the end portions of the prongs may be of sufilcient softness to permit being headed over as hereinbefore described. It will be noted that there is no attempt made to bend the prongs in either direction to clinch them into the body of the sole member, it being found that if this be attempted, the roots of the prongs are likely to be too brittle to stand such treatment. Where the prongs are arranged to be inclined toward each other, there is a tendency for such bending action to occur, although they may be slightly inclined away from each other without such tendency being noticeable. The prongs, therefore, should extend outwardly from the face of the stiffener in parallel relation or slightly diverging, where a tempered steel is employed.

While a single pair of opposed prongs arranged toward each end of the stiffener is usually preferable, more than a single pair may be employed, if desired. Such a construction is shown in Figures 7 and 8 in which the material of the stiffener displaced to form the prongs is divided into four prongs 20 which are bent up to extend from the adjacent face of the stiffener at substantially 90 angles, these prongs being arranged to be driven through the adjacent sole member and headed over, preferably within the body of this member, as previously described in connection with the single pair arrangement of the prongs.

From the foregoing description of certain embodiments of this invention, it should be evident to those skilled in the art that various changes and modifications might be made without departing from the spirit or scope of this invention as defined by the appended claims.

I claim:

1. A shoe unit comprising a fibrous sole member, a metal shank stiffener, said stiffener having a pair of integral spaced securing prongs of an initial length slightly greater than the thickness of said member, projecting through said member and headed over while maintained unbent substantially within the body of said member, said member being of sufficient softness and each prong being of such size and spaced from the other prong a distance sufficiently close to condense and grip the material of said member therebetween and sufficiently far to prevent substantial weakening of the bond between such between material and adjacent parts of said member.

2. A molded shoe unit comprising a fibrous sole member and a steel shank stiffener, said shank stiffener having a plurality of pairs of opposed spaced prongs extending into said member and headed over while maintained unbent substantially within the body of said member, said member being of sufficient softness and each prong being of such size and spaced from the other prong of its pair sufficiently closely to compress the fibrous material therebetween to effect a firm securement thereto and sufiiciently far to avoid substantial weakening of the bond between said between material and the remainder of said member.

3. A molded shoe unit comprising a fibrous sole member and a steel shank stiffener, said shank stiffener having a plurality of pairs of opposed spaced prongs extending into said member and headed over substantially within the body of said member, said member being of sufficient softness and each prong being of such size and spaced from the other prong of its pair sufficiently closely to compress the fibrous material therebetween to effect a firm securement thereto and sufficiently far to avoid substantial weakening of the bond between said between material and the remainder of said member, at least one pair of said prongs being positioned toward each end of said stiffener.

4. A shoe unit comprising a fibrous sole member, a tempered steel shank stiffener, said stiffener having apair of integral spaced securing prongs of an initial length slightly greater than the thickness of said member, projecting through said member and headed over substantially within the body of said member while maintained unbent, said member being of sufficient softness andeach prong being of such size and spaced from the other prong a distance sufliciently close to condense and grip the material of said member therebetween and suificiently far to prevent substantial weakening of the bond between such between material and adjacent parts of said member.

REINHARD B. BARTELS. 

